In addition to the doorbell feature, this product also includes motion detection. You can even set certain areas within the camera's view to NOT trigger motion detection (for example, a view corridor facing a busy street). The software that comes with the product has lots of options for how many notifications you want to get, who else can get notifications, and much more. They are selling a nifty piece of hardware, but the software that you get for no additional charge is a very nice bonus. (Disclaimer: you do have to pay an additional monthly fee if you want to save the videos made by your camera. But the audio/video doorbell function is free of any monthly fees.)